It found that most areas of a city had "excellent coverage" other regions "even quite near the centre where some if not all the networks are just not providing a data connection".

One mobile phone operator suggested that while the survey was extensive “in reality, less than two per cent of UK land mass has been surveyed overall”.

Some commentators suggested that after mobile phone companies spent a total of more than £22.5bn on the technology, they “did not have enough money left” to ensure it was rolled out across the country.

Others pointed out that many communities were against having mobile phone towers in the areas.

"For the first time consumers have the means to see 3G coverage precisely where they live, work and travel," said Gavin John, the chief executive of Epitiro, whose company worked with Ofcom, the telecoms regulator to chart mobile broadband speeds across the Britain earlier this year.

Michael Phillips, of Broadbandchoices.co.uk, a comparison website, said coverage still varied across the country.

"Mobile broadband swings between where fixed broadband was from 1998 to 2003, but many people are expecting the same speeds for their smartphones as they get at home," he said.

"The reality is that 3G is a good service in major cities but it is failing to deliver on trains and in the countryside.

Mobile phone operators broadly welcomed the findings.

A Vodaphone spokeswoman said the survey was an “interesting experiment in crowd sourcing data”.

“It adds another perspective to the maps we already provide to our customers to check the coverage in their area and across the country,” she said.

“We invest millions of pounds each year in further improving the network.

“It’s always useful to see data from such a wide base and as the volume of data increases we’ll be watching with interest and using it to help us build on our strengths and identify areas that require additional attention.”

A spokesman for O2 added: “We would like to see these types of initiatives shape the future of customer experience measurement.

“For years we have championed redefining standards in openness and transparency on network performance.”

“The issue of coverage is no longer about covering the land mass to meet a percentage target, but about depth and quality of experience.”

He added: “The results don’t show the ‘experience’ on each network – for example, speed or the ability to hold a connection.

“Simply having coverage does not guarantee a good service.”

Next year is expected to get 4G technology to power the next generation of smartphones, Ofcom announced.

Ed Richards, the regulator's chief executive, said in November last year that the long-delayed auction of additional frequencies will take place in spring 2012 and help "fuel an explosion in next generation mobile broadband".